Electronic device including MEMS devices and holed substrates, in particular of the LGA or BGA type

ABSTRACT

An electronic device includes a substrate provided with a passing opening and a MEMS device including an active surface wherein a portion of the MEMS device is integrated sensitive to chemical/physical variations of a fluid. The active surface of the MEMS device faces the substrate and is spaced therefrom, the sensitive portion being aligned to the opening. A protective package incorporates at least partially the MEMS device and the substrate, leaving at least the sensitive portion of the MEMS device, and the opening of the substrate exposed. A barrier element is positioned in an area which surrounds the sensitive portion to realize a protection structure for the MEMS device, so that the sensitive portion is free.

PRIORITY CLAIM

This application claims priority from Italian patent application No.MI2007A 000008, filed Jan. 4, 2007, and Italian patent application No.MI2007A 000007, filed Jan. 4, 2007, which are incorporated herein byreference.

TECHNICAL FIELD

Embodiments of the present invention relate generally to an electronicdevice including MEMS devices and holed substrates, in particular of theLGA or BGA type.

More specifically, embodiments of the invention relate particularly, butnot exclusively, to an electronic device including MEMS sensors mountedon an LGA substrate, wherein the MEMS sensor needs a physical interfaceof communication with the outer environment of the electronic device andthe following description is made with reference to this field ofapplication for convenience of illustration only.

BACKGROUND

As it is well known, a MEMS device (micro-electro-mechanical system) isa micro device which integrated the mechanical and electrical functionsin a silicon chip or die realized by using the lithographic techniquesof micro manufacturing. The final assembled device is typically made ofthe silicon die wherein the MEMS is integrated and, optionally, ofintegrated circuits for specific applications mounted on a substrate,for example, of the LGA or BGA type (Land Grid Array or Ball GridArray), flanked or piled onto the MEMS device, using the conventionalassembling processes.

A cover or cap fixed to the substrate, encapsulates the MEMS device andthe other integrated circuits mounted on the substrate, forming thepackage for protecting it from external physical stresses.

If the MEMS device is a pressure, gas or liquid sensor or a microphone,the cover is provided with holes for allowing the interaction betweenthe device and outside of the assembled device.

It is also known that the substrate of the LGA/BGA type is formed byconductive layers insulated from each other by means of layers ofinsulating or dielectric material. The conductive layers are shaped inconductive tracks insulated from each other by layers of insulating ordielectric material. Conductive holes, called “vias”, are typicallyrealized through the insulating layers with a vertical orientation withrespect to the layers, to form conductive paths between conductivetracks belonging to different conductive layers.

The MEMS devices are then electrically connected to the outside of thefinal device, through wires which connect contact lands provided on theMEMS devices with the conductive tracks present on the substrate insidethe cover.

Although advantageous under several aspects, these types of assembledelectronic devices including MEMS sensors require, between the cap/coverand the substrate, a welding ring.

Moreover, the formation of this cover/cap which completes the assembledelectronic device provides a series of process steps which are notprovided in the realization of integrated circuits, with a considerablecost increase.

There is a need for electronic devices including MEMS devices and havingsuch structural characteristics as to allow this electronic device to bemade with manufacturing processes of conventional integrated circuits,overcoming the limits and/or the drawbacks still limiting the electronicdevices realized according to the prior art.

SUMMARY

Embodiments of the present invention are directed to an electronicdevice including a MEMS device wherein the protective package isrealized by means of molding.

According to one embodiment, an electronic device includes a substrateprovided with a passing opening and a MEMS device including an activesurface wherein a portion of the MEMS device is integrated sensitive tochemical/physical variations of a fluid. The active surface of the MEMSdevice faces the substrate and is spaced therefrom, the sensitiveportion being aligned to the opening. A protective package, whichincorporates at least partially the MEMS device and the substrate,leaves at least the sensitive portion of the MEMS device and the openingof the substrate exposed. A barrier element is positioned in an areawhich surrounds the sensitive portion for realizing a protectionstructure for the MEMS device, so that the sensitive portion is free.

The characteristics and the advantages of electronic devices and methodsof forming such devices according to the invention will be apparent fromthe following description of embodiments thereof given by way ofindicative and non limiting example with reference to the annexeddrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

In these figures:

FIG. 1 is a sectional view of an electronic device including MEMSdevices according to a first embodiment of the invention,

FIG. 2 is a sectional view of a further version of an electronic deviceincluding MEMS devices according to another embodiment of the invention,

FIGS. 3 and 3 a are sectional views of an electronic device includingMEMS devices according to a second embodiment of the invention,

FIG. 3 b is a plan view which shows an active surface of the MEMSdevices of FIG. 3 a.

FIG. 4 is a sectional view of a further version of an electronic deviceincluding MEMS devices according to another embodiment of the invention,

FIG. 5 is a sectional view of an electronic device including MEMSdevices according to a third embodiment of the invention,

FIG. 6 is a sectional view of a further version of an electronic deviceincluding MEMS devices according to a third embodiment of the invention,

FIG. 7 is a sectional view of an electronic device including MEMSdevices according to a fourth embodiment of the invention,

FIG. 7 a is a sectional view of a further version of an electronicdevice including MEMS devices according to another embodiment of theinvention,

FIG. 8 is a sectional view of a further version of an electronic deviceincluding MEMS devices according to another embodiment of the invention,

FIGS. 9 to 20 are sectional views of applications of the electronicdevices including MEMS devices realized according to embodiments of theinvention.

DETAILED DESCRIPTION

The following discussion is presented to enable a person skilled in theart to make and use the invention. Various modifications to theembodiments will be readily apparent to those skilled in the art, andthe generic principles herein may be applied to other embodiments andapplications without departing from the spirit and scope of the presentinvention. Thus, the present invention is not intended to be limited tothe embodiments shown, but is to be accorded the widest scope consistentwith the principles and features disclosed herein.

With reference to FIG. 1, an electronic device 1 is shown for MEMSdevices according to a first embodiment of the invention which includesa substrate 2, for example of the LGA/BGA type, having an upper surface3 and a lower surface 4 opposed to the upper surface 3, provided with anopening 5 passing between these surfaces 3, 4 and including conductivetracks, at least partially interconnected with each other, formed onthese surfaces 3, 4. Moreover, lands 4 a connected to conductive trackspresent on the lower surface 4 are present on this lower portion 4. AMEMS device 6 including a die, for example of silicon, having a nonactive surface 7 and an active surface 8 opposed to the non activesurface 7. Advantageously, in the silicon die, in correspondence withthe active surface 8, a sensitive portion 9 of MEMS device 6 isintegrated. In particular, the MEMS device 6 is a sensor wherein theportion 9 is sensitive to chemical and/or physical variations of a fluidpresent outside the electronic device 1, and the fluid interacts withthe sensitive portion 9 of the MEMS device 6, through the opening 5.

According to this embodiment of the invention the active surface 8 ofthe MEMS device 6 faces the upper surface 3 of the substrate 2 and isspaced therefrom and the sensitive portion 9 is aligned to the opening5.

Moreover, the peripheral portion of the active surface 8 of the MEMSdevice 6 is provided with connection lands for the electric connectionto conductive tracks present on the upper surface 3 of the substrate 2,by means of electric connections 10, for example bumps.

Advantageously, the MEMS device 6 is electrically mounted on thesubstrate 2 by means of known “flip-chip” assembly methods.

In particular, between the active surface 8 of the MEMS device 6 and theupper surface 3 of the substrate 2 different functional areas remaindefined: a free central area 3 c aligned to the sensitive portion 9, alateral area 3 a which surrounds the free central area 3 c whereinelectric connections 10 are present which electrically couple the MEMSdevice 6 with the substrate 2, and a mean area 3 b included between thelateral area 3 a and the free central area 3 c. In particular also themean area 3 b surrounds the sensitive portion 9 of the MEMS device 6.

Also according to embodiments of the invention, the electronic device 1includes a protective package 11, realized through molding, whichincorporates the MEMS device 6, the electric connections 10 and thesubstrate 2, leaving the sensitive portion 9 of the MEMS device 6 andthe lower surface 4 and the opening 5 of the substrate 2 exposed.

In other words, the MEMS device 6 is enclosed in the protective package11.

According to embodiments of the invention, a barrier element 12 ispositioned in an area 3 b which surrounds the sensitive portion 9, i.e.,it is realized in correspondence with the mean area 3 b.

Advantageously according to embodiments of the invention, the presenceof this barrier element 12 protects the sensitive portion 9 during themanufacturing step of the protective package 11, through molding, sothat this sensitive portion 9 remains free.

In particular, in a known way, the formation of the protective package11 provides the introduction, inside a cavity of a mold, of thesubstrate 2 whereon the MEMS device 6 is mounted.

In the mold cavity the injection under pressure and at high temperatureis then provided of an electrically insulating material at the meltedstate, which will be the plastic body of the protective package 11. Thismaterial is typically a synthetic resin, for example, epoxy resin.

The proper molding step involves the injection of the resin in thecavity of the mold. This step is then followed by a cooling step forcompleting the protective package 11.

For avoiding damage by the resin of the sensitive portion 9 of the MEMSdevice 6 during the resin injection step, according to embodiments ofthe invention, between the upper surface 3 of the substrate 2 and theactive surface 8, the barrier element 12 is provided which completelysurrounds at least the sensitive portion 9 of the MEMS device 6.

Advantageously, the barrier element 12 is a ring which completelysurrounds the sensitive portion 9 of the MEMS device 6, when the MEMSdevice 6 is mounted on the substrate 2, and contacts the upper surface 3of the substrate 2 and the active surface 8.

Advantageously, the barrier element 12 is formed by welding paste,therefore, in this embodiment, the electric connection step and thegluing step of the MEMS device 6 to the substrate 2 are carried out atthe same time, resulting in a particularly compact structure of simplerealization, not needing critical alignments between differentstructures.

In this first embodiment the outer edge of this barrier element 12 iscompletely coated by the protective package 11.

Another embodiment of the device of FIG. 1 is shown with reference toFIG. 2.

Elements being structurally and functionally identical with respect tothe device described with reference to FIG. 1 will be given the samereference numbers.

In particular, in this electronic device 1 a, a protective package 11 a,realized through molding, incorporates the MEMS device 6, the electricconnections 10 and the substrate 2, leave the sensitive portion 9 andthe non active surface 7 of the MEMS device 6, as well as the lowersurface 4 and the opening 5 of the substrate 2 exposed.

With reference to FIGS. 3, 3 a and 3 b, an electronic device 1 baccording to a second embodiment of the invention is shown.

Elements being structurally and functionally identical with respect tothe device described with reference to FIG. 1 will be given the samereference numbers.

In particular, the electronic device 1 b includes a substrate 2, forexample of the LGA/BGA type, having an upper surface 3 and a lowersurface 4 opposed to the upper surface 3, provided with an opening 5. AMEMS device 6 includes a die, for example of silicon, having a nonactive surface 7 and an active surface 8 opposed to the non activesurface 7, wherein a sensitive portion 9 of a MEMS sensor is integrated.

According to this embodiment of the invention the active surface 8 ofthe MEMS device 6 faces the upper surface 3 of the substrate 2 and isspaced therefrom and the sensitive portion 9 is aligned to the opening5.

Moreover, the peripheral portion of the active surface 8 of the MEMSdevice 6 is provided with connection lands for the electric connectionto conductive tracks present on the upper surface 3 of the substrate 2,by means of electric connections 10, for example bumps.

Advantageously, the MEMS device 6 is electrically mounted on thesubstrate 2 by means of the known “flip-chip” assembly methods.

Therefore, between the active surface 8 of the MEMS device 6 and theupper surface 3 of the substrate 2 three areas are identified: a freecentral area 3 c aligned to the sensitive portion 9, a lateral area 3 awhich surrounds the free central area 3 c wherein electric connections10 are present which electrically couple the MEMS device 6 with thesubstrate 2, and a mean area 3 b included between the lateral area 3 aand the free central area 3 c.

Also according to this embodiment of the invention, the electronicdevice 1 includes a protective package 11 b, realized through molding,which incorporates the MEMS device 6, the electric connections 10 andthe substrate 2, leaving the sensitive portion 9 of the MEMS device 6and the lower surface 4 and the opening 5 of the substrate 2 exposed.

In other words, the MEMS device 6 is enclosed in the protective package11 b.

According to this embodiment of the invention, a barrier element 12 a,12 b is positioned at least in an area 3 b which surrounds the sensitiveportion 9, i.e., it is realized at least in correspondence with the meanarea 3 b.

In this second embodiment, the barrier element 12 a is an irregular area12 a formed on the upper surface 3 of the substrate 2 or the barrierelement 12 b is an irregular area 12 b formed on the active surface 8 ofthe MEMS device 6.

Advantageously, this irregular area 12 a, 12 b shows a wrinkled surface.

Advantageously, this irregular area 12 a extends on the upper surface 3of the substrate 2 in correspondence with all the circuit free area 3 c.

Advantageously, according to this embodiment of the invention thisirregular area 12 a is obtained by modifying the chemical properties ofthe upper surface 3 of the substrate 2, as shown in FIG. 3.

Advantageously, the irregular area 12 a is formed by non wettablematerial.

This layer 12 a of wettable material may be formed on the upper surface3 of the substrate 2.

As shown in FIGS. 3 a and 3 b, advantageously according to thisembodiment of the invention the barrier element 12 b is formed by anirregular area 12 b which is obtained by modifying the chemicalproperties of the active surface 8 of the MEMS device 6.

Advantageously, this irregular area 12 b extends on the active surface 8of the MEMS device 6 in correspondence with the whole sensitive portion9 of the MEMS device 6.

It is in fact known that the active surface 8 of the MEMS device 6 iscovered by a protection layer 6 a including wettable material, forexample a plastic layer, for example including organic material such asPolyimide.

According to this embodiment of the invention, from the sensitiveportion 9 of the MEMS device 6 the layer element of wettable material 6a is removed leaving a dielectric layer 12 b of the non wettable typeexposed, for example silicon oxide, which covers the sensitive portion 9of the MEMS device 6.

Advantageously, after the removal step from the sensitive portion 9 ofthe MEMS device 6 of the layer 6 a of wettable material, the MEMS device6 is welded on the substrate 2 and is subjected to a cleaning operation,for example in Plasma, by using a gas argon and oxygen mixture.

Advantageously, the oxygen of the cleaning mixture chemically reactswith the layer 6 a of wettable material increasing its wettability,while the dielectric layer 12 b which covers the sensitive portion 9 isinert to the treatment.

Therefore, as a result after the treatment an increased wettability ofthe layer 6 a of wettable material is obtained, comparable to that ofthe upper surface 3 of the substrate 2 and a reduced wettability of thesurface of the dielectric layer 12 b which covers the sensitive portion9.

This difference of wettability implies a sudden slow down of the resinflow during the molding step of the protective package 11 b thereby thesurface tension of the resin leads to the formation of a meniscus aroundthe peripheral surface of the dielectric layer 12 b which covers thesensitive portion 9.

Advantageously, as shown in FIG. 3 b, the peripheral surface of thedielectric layer 12 b is of circular shape.

The barrier layer 12 b of non wettable material may be formed only onthe active surface 8 of the upper MEMS device 3 of the substrate 2 ofthe sensitive portion 9.

In a further version of this second embodiment of the invention theirregular area 12 a, 12 b shows some wrinkles.

Advantageously, in the irregular area 12 a, 12 b trenches are formed inthe substrate or in the MEMS device 6, so as to realize a preferred pathdefined in the substrate or on the MEMS device 6 for the resin duringthe molding step.

Advantageously, these trenches completely surround the sensitive portion9 of the MEMS device 6.

Advantageously, in this latter embodiment a layer of non wettablematerial can be present in correspondence with the sensitive portion 9of the MEMS device 6 in the area surrounded by the trenches.

According to this embodiment of the invention, the presence of thisirregular area 12 a, 12 b protects the sensitive portion 9 during themanufacturing step of the protective package 11 a, through molding,having the liquid resin uniformly distributed around the electricconnections without reaching the sensitive portion 9.

An embodiment of the device of FIG. 3 is shown with reference to FIG. 4.

Elements being structurally and functionally identical with respect tothe device described with reference to FIG. 3 will be given the samereference numbers.

In particular, in this electronic device 1 c, a protective package 11 c,realized through molding, incorporates the MEMS device 6, the electricconnections 10 and the substrate 2, leaving the sensitive portion 9 andthe non active surface 7 of the MEMS device 6, as well as the lowersurface 4 and the opening 5 of the substrate 2 exposed.

With reference to FIG. 5, an electronic device 1 d according to a thirdembodiment of the invention is shown.

Elements being structurally and functionally identical with respect tothe device described with reference to FIG. 1 will be given the samereference numbers.

In particular, in this embodiment an underfiller 13 is present in thelateral area 3 a so as to incorporate the electric connections 10 formechanically strengthening the electronic device 1 in the connectionarea between the MEMS device 6 and the substrate 2.

Advantageously, the underfiller 13 is epoxy resin.

Advantageously, the underfiller 13 shows a profile tapered outwards withrespect of the lateral area 3 a on the opposite side with respect to themean area 3 b, while it shows a substantially vertical profile incorrespondence with the mean area 3 b.

In other words, the cross section of the underfiller 13 increases whenapproaching the upper surface 3 of the substrate 2.

The electronic device 1 d also includes a protective package 11 d,realized through molding, which incorporates the MEMS device 6, theunderfiller 13 and the substrate 2, leaving the sensitive portion 9 ofthe MEMS device 6 and the lower surface 4 and the opening 5 of thesubstrate 2 exposed.

The presence of the barrier material 12 allows maintaining the sensitiveportion 9 of the MEMS device 6, i.e., the central free area 3 c, freefrom the underfiller 13.

Moreover, the underfiller 13 protects the active surface 8 of the MEMSdevice 6 during the manufacturing step of the plastic package 11 d.

An embodiment of the device of FIG. 5 is shown with reference to FIG. 6.

Elements being structurally and functionally identical with respect tothe device described with reference to FIG. 5 will be given the samereference numbers.

In particular, in this electronic device 1 e, a protective package 11 e,realized through molding, incorporates the MEMS device 6, theunderfiller 13 and the substrate 2, leaving the sensitive portion 9 andthe non active surface 7 of the MEMS device 6, as well as the lowersurface 4 and the opening 5 of the substrate 2 exposed.

With reference to FIG. 7, an electronic device 1 f according to a fourthembodiment of the invention is shown.

Elements being structurally and functionally identical with respect tothe device described with reference to FIG. 3 will be given the samereference numbers.

In particular, in this embodiment an underfiller 13 is present in thelateral area 3 a so as to incorporate the electric connections 10 tomechanically strengthen the electronic device 1 in the connection areabetween the MEMS device 6 and the substrate 2.

Advantageously, the underfiller 13 shows a tapered profile outside thelateral area 3 a on the opposite side with respect to the mean area 3 b,while it shows a substantially vertical profile in correspondence withthe mean area 3 b.

In other words, the cross section of the underfiller 13 increases whenapproaching the upper surface 3 of the substrate 2.

The electronic device 1 f also includes a protective package 11 f,realized through molding, which incorporates the MEMS device 6, theunderfiller 13 and the substrate 2, leaving the sensitive portion 9 ofthe MEMS device 6 and the lower surface 4 and the opening 5 of thesubstrate 2 exposed.

The presence of the barrier element 12 a allows maintaining thesensitive portion 9 of the MEMS device 6 free from the underfiller 13.

A further embodiment of the device of FIG. 7 is shown with reference toFIG. 7 a.

Elements being structurally and functionally identical with respect tothe device described with reference to FIG. 7 will be given the samereference numbers.

In this embodiment the barrier element 12 b is formed on the activesurface 8 of the MEMS device 6 around the sensitive portion 9, prior tothe formation of the underfiller 13, with the same modes with which thebarrier element 12 b of FIG. 3 a is realized.

In particular, the difference of wettability between the barrier element12 b and the portion outside the barrier layer implies a sudden slowdown of the flow of the underfiller 13 during its dispensing step afterthe MEMS device 6 has been fixed to the substrate, thereby the surfacetension of the underfiller 13 leads to the formation of a meniscusaround the peripheral surface of the barrier element 12 b which at leastsurrounds the sensitive portion 9.

An embodiment of the device of FIG. 7 is shown with reference to FIG. 8.

Elements being structurally and functionally identical with respect tothe device described with reference to FIG. 7 will be given the samereference numbers.

In particular, in this electronic device 1 g, a protective package 11 g,realized through molding, incorporates the MEMS device 6, theunderfiller 13 and the substrate 2, leaving the sensitive portion 9 andthe non active surface 7 of the MEMS device 6, as well as the lowersurface 4 and the opening 5 of the substrate 2 exposed.

In particular, in this embodiment an underfiller 13 is present in thelateral area 3 a so as to incorporate the electric connections 10 tomechanically strengthen the electronic device 1 in the connection areabetween the MEMS device 6 and the substrate 2.

With reference to FIGS. 9 and 10, two further versions of an electronicdevice 1 h according to the first embodiment of the invention are shown.

Elements being structurally and functionally identical with respect tothe device described with reference to FIG. 1 will be given the samereference numbers.

In particular, the electronic device 1 h includes an integrated circuit14 having a first surface 14 a and a second surface 14 b opposed to thefirst surface, the integrated circuit 14 being mounted with the firstsurface 14 a on the non active surface 7 of the MEMS device 6.

The integrated circuit 14 is thus electrically connected to theconductive tracks present on the upper surface 3 of the substrate 2 bymeans of further electric connections 15.

For example, the dimension of the cross section of this integratedcircuit 14 is greater than the dimension of the cross section of theMEMS device 6.

Advantageously, as shown in FIG. 9, on the first surface 14 a apassivated circuitry is integrated and moreover the first surface 14 ais provided with connection lands for the electric connection to theMEMS device 6, by means of bumps.

Advantageously, as shown in FIG. 10, on the second surface 14 b apassivated circuitry is integrated and moreover connection lands areprovided for the electric connection to the MEMS device 6 throughwire-bonding.

A protective package 11 h, realized through molding, incorporates theMEMS device 6, the integrated circuit 14, the connections 15 and thesubstrate 2, leaving the sensitive portion 9 and the non active surface7 of the MEMS device 6, as well as the lower surface 4 and the opening 5of the substrate 2 exposed.

With reference to FIGS. 11 and 12, two further versions are shown of anelectronic device 1 g according to the third embodiment of theinvention.

Elements being structurally and functionally identical with respect tothe device described with reference to FIG. 5 will be given the samereference numbers.

In particular, the electronic device 1 g includes an integrated circuit14 having a first surface 14 a and a second surface 14 b opposed to thefirst surface, which is mounted with the first surface 14 a on the nonactive surface 7 of the MEMS device 6.

The integrated device 14 is then electrically connected to theconductive tracks formed on the upper surface 3 of the substrate 2 bymeans of further electric connections 15.

Advantageously, the dimension of the cross section of this integratedcircuit 14 is greater than the dimension of the cross section of theMEMS device 6.

Advantageously, the underfiller 13 is also present in an area 14 cincluded between a portion of the first surface 14 a projecting withrespect to the MEMS device and the upper surface 3 of the substrate 2.

Advantageously, the underfiller 13 shows a tapered profile outside thearea 14 c.

In other words the cross section of the underfiller 13 increases whenapproaching the upper surface 3 of the substrate 2.

Advantageously, as shown in FIG. 11, the first surface 14 a is providedwith connection lands for the electric connection to the MEMS device 6,by means of bump (flip-chip) bonding.

Advantageously, as shown in FIG. 12, the second surface 14 b is providedwith connection lands for the electric connection to the MEMS device 6,by means of connection wires (wirebonding).

A protective package 11 g, realized through molding, incorporates theMEMS device 6, the integrated circuit 14, the connections 15, theunderfiller 13 and the substrate 2, leaving the sensitive portion 9 andthe non active surface 7 of the MEMS device 6, as well as the lowersurface 4 and the opening 5 of the substrate 2 exposed.

The presence of the underfiller 13 allows to protect both the integratedcircuit 14 and the MEMS device 6 during the molding step of theprotective package 11 g.

With reference to FIG. 13 the electronic device 1 i is shown which is afurther version of the electronic device of FIG. 9, wherein theprotective package 11 i leaves the second surface 14 b of the integratedcircuit 14 exposed.

With reference to FIG. 14 the electronic device 1 l is shown which is afurther embodiment of the electronic device of FIG. 11, wherein theprotective package 11 l leaves the second surface 14 b of the integratedcircuit 14 exposed.

With reference to FIG. 15, the device 1 of FIG. 1 is shown wherein anintegrated circuit 16 is mounted on the substrate 2 flanked by the MEMSdevice 6, and fixed to the substrate 2, for example by means of awelding layer 16 b.

The integrated circuit 16 is electrically connected to the substrate 2by means of further electric connections 16 a.

The protective package 11, realized through molding, incorporates theMEMS device 6 with the electric connections 10, the integrated circuit16 with the electric connections 16 a and the substrate 2, leaving thesensitive portion 9 of the MEMS device 6, as well as the lower surface 4and the opening 5 of the substrate 2 exposed.

With reference to FIG. 16, the device 1 d of FIG. 5 is shown wherein anintegrated circuit 16 is mounted on the substrate 2 flanked to the MEMSdevice 6, and fixed to the substrate 2, for example by means of awelding layer 16 b.

The integrated circuit 16 is electrically connected to the substrate 2by means of further electric connections 16 a.

The protective package 11 d, realized through molding, incorporates theMEMS device 6, the underfiller 13, the integrated circuit 16 with thefurther electric connections 16 a and the substrate 2, leaving sensitiveportion 9 of the MEMS device 6, as well as the lower surface 4 and theopening 5 of the substrate 2 exposed.

With reference to FIG. 17, the device 1 a of FIG. 2 is shown wherein anintegrated circuit 16 is mounted on the substrate 2 flanked to thedevice MEMS 6, and fixed to the substrate 2, for example by means of awelding layer 16 b.

The integrated circuit 16 is electrically connected to the substrate 2by means of further electric connections 16 a.

The protective package 11 a, realized through molding, incorporates theMEMS device 6 with the electric connections 10, the integrated circuit16 with the further electric connections 16 a and the substrate 2,leaving the sensitive portion 9 and the non active surface 7 of the MEMSdevice 6, as well as the lower surface 4 and the opening 5 of thesubstrate 2 exposed.

With reference to FIG. 18, the device 1 e of FIG. 6 is shown wherein anintegrated circuit 16 is mounted on the substrate 2 flanked to the MEMSdevice 6, and fixed to the substrate 2, for example by means of awelding layer 16 b.

The integrated circuit 16 is electrically connected to the substrate 2by means of further electric connections 16 a.

The protective package 11 e, realized through molding, incorporates theMEMS device 6, the underfiller 13, the integrated circuit 16 with thefurther electric connections 16 a and the substrate 2, leaving thesensitive portion 9 and the non active surface 7 of the MEMS device 6,as well as the lower surface 4 and the opening 5 of the substrate 2exposed.

With reference to FIG. 19, the device 1 h of FIG. 9 is shown wherein asecond integrated circuit 16 is mounted on the substrate 2 flanked tothe MEMS device 6, and fixed to the substrate 2, for example by means ofa welding layer 16 b.

The second integrated circuit 16 is electrically connected to thesubstrate 2 by means of further electric connections 16 a.

A third integrated circuit 17 is mounted on the second surface 14 b ofthe integrated circuit 14, and electrically connected to the substrate 2by means of further electric connections 17 a.

A fourth integrated circuit 18 is mounted on the second integratedcircuit 16 and electrically connected to the substrate 2 by means offurther electric connections 18 a.

The protective package 11 h, realized through molding, incorporates theMEMS device 6, the electric connections 10, the integrated circuits 14,16, 17 and 18 with the relative electric connections 15, 16 a, 17 a and18 a and the substrate 2, leaving the sensitive portion 9 of the MEMSdevice 6, as well as the lower surface 4 and the opening 5 of thesubstrate 2 exposed.

With reference to FIG. 20, the device 1 g of FIG. 11 is shown wherein asecond integrated circuit 16 is mounted on the substrate 2 flanked tothe MEMS device 6, and fixed to the substrate 2, for example by means ofa welding layer 16 b.

The second integrated circuit 16 is electrically connected to thesubstrate 2 by means of further electric connections 16 a.

A third integrated circuit 17 is mounted on the second surface 14 b ofthe integrated circuit 14, and electrically connected to the substrate 2by means of further electric connections 17 a.

A fourth integrated circuit 18 is mounted on the second integratedcircuit 16 and electrically connected to the substrate 2 by means offurther electric connections 18 a.

The protective package 11 g, realized through molding, incorporates theMEMS device 6, the underfiller 13, the integrated circuits 14, 16, 17and 18 with the relative electric connections 15, 16 a, 17 a and 18 aand the substrate 2, leaving the sensitive portion 9 of the MEMS device6, as well as the lower surface 4 and the opening 5 of the substrate 2exposed.

Advantageously, the integrated circuits 14, 16, 17 and 18 can be sensordevices, for example accelerometers 14, gyroscopes 18, magnetometers 17to form an IMU (inertial measurement unit).

These integrated circuits can be put in different configurations insidethe protective package on the basis of their dimensions and geometricfeatures.

With devices according to embodiments of the invention it is possible torealize microphones, pressure, gas, chemical sensors, which areencapsulated in a protective package realized by means of molding. Thesedevices can, in turn, be contained in a variety of different types ofelectronic systems, such as barometric systems, audio systems, computersystems, control systems, safety systems, and so on.

It is then possible to integrate more sensors (accelerometers andpressure sensors) in the same protective package 11, for example torealize the IMU, or for barometric stations by integrating, for example,a pressure sensor and a humidity sensor.

Advantageously, in electronic devices according to one embodiment of theinvention and previously described, the electronic device as a wholeshows an overall dimension included between 3×3×1 mm^3, while the MEMSdevice 6 has a width of 1500 μm a length of 1500 μm and a thickness of700 μm.

The sensitive portion 9 of the MEMS device 6 has a diameter includedbetween 100 μm and 1000 μm.

The distance between the active surface 8 of the MEMS device 6 and theupper surface 3 of the substrate is included between 50 and 500 μm,while the thickness of the substrate is included between about 150 and300 μm and the width of the opening 5 is included between 100 and 700μm.

If the barrier element 12 is realized with a ring of welding paste ithas a thickness of a cross section included between 60 and 300 μm.

If the barrier element 12 a, 12 b is realized with an irregular area ithas a width of a cross section of about 10-50 μm and, for example, adepth included between 20-80 μm.

In conclusion, electronic devices according to embodiments of theinvention are particularly compact and use technical solutions which donot provide critical alignments. Advantageously according to embodimentsof the invention, the presence of the barrier element 12, 12 a allowsprotecting the sensitive portion 9 of the MEMS device 6 during themanufacturing steps of the protective package 11 or during thedispensing step of the underfiller 13 in the electronic device 1according to the invention.

In particular, according to embodiments of the invention, this barrierelement 12, 12 a, 12 b can be of physical or chemical nature or acombination of the two.

These barrier elements 12, 12 a, 12 b can be realized both on thesubstrate 2 and on the MEMS device 6.

From the foregoing it will be appreciated that, although specificembodiments of the invention have been described herein for purposes ofillustration, various modifications may be made without deviating fromthe spirit and scope of the invention.

1. An electronic device, comprising: a substrate provided with a passingopening, a MEMS device comprising an active surface wherein a portion ofsaid MEMS device is integrated to be sensitive to chemical/physicalvariations of a fluid, wherein said active surface of said MEMS devicefaces said substrate and is spaced therefrom, said sensitive portionbeing aligned to said opening, and in that it also comprised: anon-semiconductor protective package, which incorporates at leastpartially said MEMS device and said substrate, leaving at least saidsensitive portion of said MEMS device, and said opening of the substrateexposed; and a barrier element positioned in an area which surroundssaid sensitive portion for realizing a protection structure for saidMEMS device, so that said sensitive portion is free.
 2. The electronicdevice according to claim 1, wherein said barrier element comprises aring that is in contact with the surface of said substrate and with theactive surface of said MEMS device, and whose external edge iscompletely coated by said protective package.
 3. The electronic deviceaccording to claim 1, wherein said barrier element comprises weldingpaste.
 4. The electronic device according to claim 1, wherein saidbarrier element comprises an irregular area formed on the surface of thesubstrate.
 5. The electronic device according to claim 4, wherein thisirregular area extends on the surface of said substrate incorrespondence with said sensitive portion.
 6. The electronic deviceaccording to claim 4, wherein this irregular area is obtained bymodifying the chemical properties of the surface of the substrate. 7.The electronic device according to claim 4, wherein said irregular areais formed by a non-wettable material.
 8. The electronic device accordingto claim 1, wherein electric connections which electrically couple saidMEMS device with said substrate are present outside said barrier elementwith respect to said sensitive portion.
 9. The electronic deviceaccording to claim 8, wherein an underfiller incorporates said electricconnections.
 10. The electronic device according to claim 8, whereinsaid electric connections comprise bumps.
 11. The electronic deviceaccording to claim 1, wherein said MEMS device is mounted on saidsubstrate by means of the known “flip-chip” assembling method.
 12. Theelectronic device according to claim 1, wherein said MEMS device iscompletely enclosed in said protective package.
 13. The electronicdevice according to claim 1, wherein said protective package leaves alsothe non active surface of said MEMS device exposed.
 14. The electronicdevice according to claim 9, wherein said underfiller shows a taperedprofile outside said peripheral area, while it shows a substantiallyvertical profile in correspondence with said area which surrounds saidsensitive portion.
 15. The electronic device according to claim 1,further comprising integrated circuits mounted flanked or piled onto theMEMS device.
 16. The electronic device according to claim 15, whereinsaid integrated circuits are electrically connected to conductive trackspresent on said substrate, by means of further electric connections. 17.The electronic device according to claim 15, wherein said protectivepackage incorporates said integrated circuits and said further electricconnections.
 18. The electronic device according to claim 1, whereinsaid substrate is of the LGA type.
 19. The electronic device accordingto claim 1, wherein said substrate is of the BGA type.
 20. Theelectronic device according to claim 1, wherein said MEMS devicecomprises a pressure sensor.
 21. The electronic device according toclaim 1, wherein said MEMS device comprises a gas sensor.
 22. Theelectronic device according to claim 1, wherein said MEMS devicecomprises a chemical sensor.
 23. The electronic device according toclaim 1, wherein the protective package is realized through molding. 24.The electronic device according to claim 1, wherein said barrier elementcomprises an irregular area formed on the active surface of the MEMSdevice.
 25. The electronic device according to claim 24, wherein thisirregular area extends on the sensitive portion of the MEMS device. 26.The electronic device according to claim 24, wherein this irregular areais obtained by modifying the chemical properties around/of the activesurface of the MEMS device.
 27. The electronic device according to claim24, wherein this irregular area is formed by non wettable material. 28.The electronic device according to claim 27, wherein the MEMS devicecomprises a protection layer on the active surface wherein saidirregular area is formed by means of removal of said protection layerfrom the sensitive portion of the MEMS device exposing said layer of nonwettable material.
 29. The electronic device according to claim 28,wherein said protection layer is Polyimide and said layer of nonwettable material is oxide.
 30. An electronic device, comprising: asubstrate provided with a passing opening, a MEMS device comprising anactive surface wherein a portion of said MEMS device is integrated to besensitive to chemical/physical variations of a fluid, wherein saidactive surface of said MEMS device faces said substrate and is spacedtherefrom, said sensitive portion being aligned to said opening, and inthat it also comprised: a protective package, which incorporates atleast partially said MEMS device and said substrate, leaving at leastsaid sensitive portion of said MEMS device, and said opening of thesubstrate exposed; and a barrier element comprising an irregular areaformed on the surface of the substrate positioned in an area whichsurrounds said sensitive portion for realizing a protection structurefor said MEMS device, so that said sensitive portion is free; whereinsaid irregular area comprises trenches which form preferred paths duringthe formation steps of the protective package.
 31. The electronic deviceaccording to claim 4, wherein a layer of non wettable material is formedin correspondence with said sensitive portion of said MEMS device. 32.The electronic device according to claim 9, wherein a barrier elementprotects the sensitive portion during the formation of said underfiller.33. An electronic device, comprising: a substrate including a passingopening; a die coupled to the substrate, the die including an activesurface and the active surface including a sensitive portion positionedadjacent the passing opening of the substrate and the die being operableto sense a physical parameter of a medium to which the sensitive portionis exposed through the passing opening; a protective package housing thesubstrate and the die; and a barrier element formed surrounding thesensitive portion to isolate the sensitive portion from the protectivepackage.
 34. The electronic device of claim 33, wherein the barrierelement comprises a ring formed adjoining a surface of the substrate andthe active surface of die.
 35. The electronic device of claim 34,wherein the barrier element includes a periphery surface that iscompletely covered by the protective package.
 36. The electronic deviceof claim 33, wherein the barrier element comprises an irregular areaformed on a surface of the substrate surrounding and adjacent to thepassing opening.
 37. The electronic device of claim 33, wherein thebarrier element comprises an irregular area formed on the active surfaceof the die surrounding the sensitive portion.
 38. The electronic deviceof claim 33, wherein the die comprises a MEMS device.
 39. The electronicdevice of claim 33, wherein the medium comprises a fluid.
 40. Theelectronic device of claim 39, wherein the physical parameter of thefluid comprises a chemical property of the fluid.
 41. The electronicdevice of claim 33, further comprising at least one additional dieelectronically coupled to the substrate.
 42. The electronic device ofclaim 41, wherein at least one additional die is formed on the substrateflanking the die.
 43. An electronic system, comprising: electroniccircuitry including a sensor, the sensor including, a substrateincluding a passing opening; a die coupled to the substrate, the dieincluding an active surface and the active surface including a sensitiveportion positioned adjacent the passing opening of the substrate and thedie being operable to sense a physical parameter of a medium to whichthe sensitive portion is exposed through the passing opening; aprotective package housing the substrate and the die; and a barrierelement formed surrounding the sensitive portion to isolate thesensitive portion from the protective package.
 44. The electronic systemof claim 43, wherein the sensor comprises one of a microphone, pressuresensor, gas sensor, flow sensor, and pH sensor.
 45. The electronicsystem of claim 43, wherein the electronic circuitry comprises one ofbarometric circuitry, audio circuitry, computer circuitry, controlcircuitry, test equipment circuitry, or safety system circuitry.